Fix delay_divisor value for proper delay(9) on 68040.

tsutsui · Jan 20, 2023 · 883462c · 883462c
1 parent b9f95d7
commit 883462c
Show file tree

Hide file tree

Showing 3 changed files with 16 additions and 40 deletions.
diff --git a/sys/arch/next68k/include/cpu.h b/sys/arch/next68k/include/cpu.h
@@ -120,9 +120,6 @@ void	loadustp(int);
 void	doboot(void) __attribute__((__noreturn__));
 int	nmihand(void *);
 
-/* clock.c functions */
-void	next68k_calibrate_delay(void);
-
 #endif /* _KERNEL */
 
 #define NEXT_RAMBASE  (0x4000000) /* really depends on slot, but... */

diff --git a/sys/arch/next68k/next68k/clock.c b/sys/arch/next68k/next68k/clock.c
@@ -48,38 +48,6 @@ __KERNEL_RCSID(0, "$NetBSD: clock.c,v 1.12 2010/04/24 19:58:13 dbj Exp $");
  * -- jewell@mit.edu
  */
 
-/*
- * Note that the value of delay_divisor is roughly
- * 2048 / cpuspeed (where cpuspeed is in MHz) on 68020
- * and 68030 systems.  See clock.c for the delay
- * calibration algorithm.
- */
-int	cpuspeed;		  /* relative cpu speed; XXX skewed on 68040 */
-int	delay_divisor = 2048/25;  /* delay constant */
-
-/*
- * Calibrate the delay constant.
- */
-void
-next68k_calibrate_delay(void)
-{
-	extern int delay_divisor;
-
-	/* @@@ write this once we know how to read
-	 * a real time clock
-	 */
-
-	/*
-	 * Sanity check the delay_divisor value.  If we totally lost,
-	 * assume a 25MHz CPU;
-	 */
-	if (delay_divisor == 0)
-		delay_divisor = 2048 / 25;
-
-	/* Calculate CPU speed. */
-	cpuspeed = 2048 / delay_divisor;
-}
-
 int clock_intr(void *);
 
 int

diff --git a/sys/arch/next68k/next68k/machdep.c b/sys/arch/next68k/next68k/machdep.c
@@ -168,6 +168,17 @@ phys_seg_list_t phys_seg_list[VM_PHYSSEG_MAX];
 phys_ram_seg_t mem_clusters[VM_PHYSSEG_MAX];
 int	mem_cluster_cnt;
 
+/*
+ * On the 68020/68030, the value of delay_divisor is roughly
+ * 2048 / cpuspeed (where cpuspeed is in MHz).
+ *
+ * On the 68040/68060(?), the value of delay_divisor is roughly
+ * 759 / cpuspeed (where cpuspeed is in MHz).
+ * XXX -- is the above formula correct?
+ */
+int	cpuspeed = 33;		  /* relative cpu speed; XXX skewed on 68040 */
+int	delay_divisor = 759 / 33;  /* delay constant; assume fastest 33 MHz */
+
 /****************************************************************/
 
 /*
@@ -208,9 +219,6 @@ next68k_init(void)
 		}
 	}
 
-	/* Calibrate the delay loop. */
-	next68k_calibrate_delay();
-
 	/*
 	 * Initialize error message buffer (at end of core).
 	 */
@@ -256,8 +264,6 @@ consinit(void)
 		}
 
 		init = 1;
-	} else {
-		next68k_calibrate_delay();
 	}
 }
 
@@ -316,16 +322,21 @@ void
 identifycpu(void)
 {
 	const char *mc, *mmu_str, *fpu_str, *cache_str;
+	extern int turbo;
 
 	/*
 	 * ...and the CPU type.
 	 */
 	switch (cputype) {
 	case CPU_68040:
 		mc = "40";
+		cpuspeed = turbo ? 33 : 25;
+		delay_divisor = 759 / cpuspeed;
 		break;
 	case CPU_68030:
 		mc = "30";
+		cpuspeed = 25;
+		delay_divisor = 2048 / cpuspeed;
 		break;
 	case CPU_68020:
 		mc = "20";